I have had my ciss for about a year, worked good for many months, now I have had problems with my epson NX515 printing cyan, quality went south, run print head cleaning several times, test print looks good, print a week or so, then cyan drops out again, try cleaning heads several times, now no cyan comes out at all in nozzle check print.. I checked ink flow from CISS - looks good, I made sure cyan cartridge was full, still no luck, any ideas??

If there one color isn't printing, then most likely there is something obstructing it from flowing. First, you should make sure that all the air filters are installed into the ink tanks (they go into the smaller hole). Then go through these steps to get the color going:

1) Take the cartridges out and locate the little 'spikes' inside the printer carriage that 'poke' into the bottom of the cartridges and draw ink from them.2) Take a napkin with a little bit of rubbing alcohol in it and 'wipe down' the spikes, focusing on the color that isn't coming out. Try not to get rubbing alcohol into the 'spikes'3) Reinsert the cartridges back in.4) Print one nozzle check; find out which color isnít coming out.5) Do one head cleaning.6) Repeat step 4 and compare it with the first nozzle check.7) If it looks the same, do one more head cleaning.7) Let the printer sit for 4-5 hours so the color can fill up on the print head. Repeat steps 4-7 if you find cyan still isn't coming out.